This project is focused on functional studies of NK receptor and T cell receptor recognition. Our approaches include: 1) the development and characterization of mouse strains transgenic for pathogenic T cell receptors--the animals develop autoimmune gastritis, a model for pernicious anemia; 2) correlation of MHC/peptide and MHC/peptide/TCR affinity with immunogenicity in a model murine tumor system; 3) evaluation of approaches to manipulate the TCR repertoire in an antigen-specific immune response. With respect to the first project, we have cloned and expressed a two different TCR from T cell clones that show specificity for two peptides from the gastric H/K ATPase. One of these clones causes a Th1 type disease, and the other a Th2 disease. Transgenic animals expressing the TCR from each of these clones have been produced and have been analyzed. The transgenic derived from the Th1 clone, TXA23, develops a fulminant autoimmune gastritis within 10 days of birth. The transgenic derived from the Th2 clone, TXA51, appears to have a less fulminant disease. Studies are underway to evaluate quantitatively the role of background genes as well as the cellular and molecular details of these differences. In the second model system, we have explored a panel of peptides that are analogs of a murine H-2Ld restricted tumor cell called AH1. Studies using recombinant H-2Ld and a recombinant form of the AH1 alpha/beta T cell receptor have identified a variant peptide that appears to generate an MHC/peptide complex that is of higher affinity for the cognate TCR than the parental peptide. When tested in a tumor prevention system, this peptide was a more effective immunogen for tumor specific cytolytic T cells. The third model system has taken advantage of our ability to visualize MHC-I reactive T cells in vivo using MHC/peptide tetramers. Animals immunized with viral vectors encoding the H-2Dd restricted antigenic peptide, HIV IIIB gp120 P18-I10 produced specific CTL against this antigen in the context of H-2Dd. These V beta family representation of the antigen-specific cells could be specifically skewed if the animals were injected at around the time of immunization with a monoclonal antibody directed agaisnt the specific MHC/peptide complex. Thus, specific T cell responses can be diverted by such monoclonal antibodies. This offers new ways to alter the T cell response in autoimmune states.